Supplemental Figure 4 Sensitivity analyses of model simulations were performed by holding all other inputs constant and varying only the parameter of interest. The dark blue line is the model results with the default parameters, observations are shown in gray, and the light blue uncertainty bounds reflect the model results from varying DIC of the deep ocean (1.7-2.7 mol/kg) (A), DIC of the EUC (2.0-2.1 mol/kg) (B), pre-bomb radiocarbon levels in the deep ocean (-110‰ to -80‰) (C), mixed-layer depth (15-50m) (D), and surface biological uptake (8x10-5molC/m3/day-8x10-3molC/m3/day) (E).